Women could be undergoing unnecessary breast cancer surgery after having MRI
scans because the technique is too sensitive and picks up harmless growths,
an expert said today (FRI).

Magnetic resonance mammography (MRM) is particular good at finding tumours that are hard to spot using standard x-ray mammography.

Younger women with a genetically high risk of breast cancer can be offered MRMs on the NHS if recommended by a clinician.

But Malcolm Kell, a consultant surgeon at the Eccles Breast Screening Unit at University Hospital, Dublin, said there was "no compelling evidence that this technique should be routinely used in newly diagnosed breast cancer".

While he said MRM was invaluable for assessing advanced breast cancer and to assess responses to chemotherapy, he argued in the British Medical Journal that its routine use at an early stage could do more harm than good.

The only robust trial of its use in the management of early stage breast cancer showed that it failed to reduce the proportion of women (19 per cent) who had to return for a second operation because initial surgery had not removed all the potentially cancerous tissue.

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The number who consequently had a mastectomy was seven times higher (seven per cent compared to one per cent) in those who had an MRM, while there was no evidence that the increased rate of more aggressive surgery had saved lives.

Prof Kefah Mokbel, a consultant breast surgeon at St George's Hospital and the London Breast Institute at the Princess Grace Hospital, said about one in four indications of breast cancer from MRMs was inaccurate, known as a "false positive".

But he said it was an essential tool for checking younger women with firmer breasts who were at a high genetic risk of cancer.

A study published in The Lancet in 2007 found MRI scans picked up 92 per cent of early lesions, which could lead to breast cancer, compared to only 56 per cent by x-ray mammography.